Abstract: Based on the dynamic governing equations in unsaturated soils,one kind of the granular three-phase materials,solutions of wave equations are carried out,which demonstrates the existence of three types of P waves(P₁,P₂ and P₃ wave) and one type of S wave.Analytic expressions for wave velocity and attenuation are proposed.Taking tailings in actual engineering for instance,this paper makes numerical analysis about the dispersion characteristics of elastic wave in unsaturated soils by using Matlab.Some typical dispersion and attenuation curves are given.The results show that the velocity and attenuation of all four types of waves becomes higher with the frequency increasing in a range.Frequency has much greater effect on the velocity and attenuation of P₂ and P₃ wave than P₁ and S wave.The velocity of P₁ wave becomes higher with the degree of saturation increasing.Saturation has small effect on P₂,P₃ and S wave.